Mr. T Sudhakar Deputy Manager Indian Oil Corporation Limited, India - PowerPoint PPT Presentation

Novel approach of Continuous Catalytic Reforming Unit Capacity augmentation Mr. T Sudhakar Deputy Manager Indian Oil Corporation Limited, India

Abstract: Novel approach of Continuous Catalytic Reforming Unit (CCRU) capacity augmentation Description: CCRU revamp for capacity augmentation is conventionally performed by addition of new reactor and furnace along with associated modifications. This type of capacity augmentation revamp not only requires high number of shutdown days, but calls for high Capex and Opex. This paper talks about novel approach implemented at Mathura Refinery, Indian Oil Corporation limited, India to augment the CCRU capacity significantly without any major modification in CCRU. Case Study: Crude processing capacity at Mathura Refinery necessitated capacity augmentation of CCRU by at least 20 %. Feedstock to CCRU contains about 4.0 vol % of benzene and its precursors, as a result approx 12 vol % of product reformate was sacrificed as light reformate draw in order to maintain benzene content in heavy reformate stream to the desired level of < 1.8 vol % to meet MS specifications. A study was done for CCRU capacity augmentation by (a) changing the design of CCRU reactor internals -replacement of single concentric outer Johnson-screen by multiple scallop design (b) low cost revamp of Naphtha splitter unit (NSU) to improve CCRU feed quality. Replacement of reactors internals design, allowed loading of 22 % additional catalyst with increase in T’put by corresponding amount. Low cost NSU revamp envisaged addition of preheat exchanger, overhead condensers and product coolers along with modification of column internals. Post NSU revamp, the benzene and its precursors in CCRU feed was found to be in the range of 0.2-0.3 vol % against the original level of 4.0 vol %. With this CCRU feedstock, the benzene in reformate stream is maintained well within the desired limit of < 1.8 Vol %, resulting in stoppage of reformer splitter unit (RSU). Conclusion: The innovative approach of low cost CCRU capacity augmentation through changing the design of the reactor internals, along with naphtha splitter unit revamp and stoppage of RSU in an integrated manner resulted in 20 % increase in CCRU capacity in addition to 12 % reformate yield improvement due to stoppage of RSU. Thus not only the combined reformate yield has improved by 32 % but there has been significant energy reduction due to stoppage of RSU and light reformate processing in ISOM unit.

Introduction  Surge in MS demand necessitates capacity augmentation of existing catalytic reforming unit (CRU)  Refiners normally use high octane heavy reformate stream ex CRU as main MS blend stock to meet octane requirement in final MS pool  Reformate yield improvement become the key driver in maximizing octane barrels  Low benzene reformate became critical to meet current Euro IV MS specifications

CCRU at Mathura Refinery  Design capacity : 466 TMTPA  Design reformate RON : 98  Feedstock : 90-150 0 c naphtha cut  Design feedstock,N+2A : 66-96 vol %  Catalyst inventory : 40 MT of CR401 catalyst ( 33 MT in reactors and 7 MT in regenerator )  Process Licensor : M/s Axens

Necessity for CCRU capacity augmentation at Mathura Refinery, IOCL, India Naphtha dispatched as-such as low margin product due to CCRU capacity limitation Change in refinery crude basket makes CCRU feed poorer. N+2A became 52 vol% against design of 66-96 vol % Poor feedstock affected reformate RON (95-96 against design 98) High content of benzene & its precursors (MCP and CH ) in CCRU feed led to reformate rich in benzene (4 vol%) High benzene reformate resulted in loss of 12 vol % of reformate yield (as light reformate) to meet MS specifications Situation affected octane barrels and necessitated CCRU capacity augmentation by at least 20 %

Conventional CCRU Capacity Augmentation  Conventional way of CCRU capacity augmentation envisages addition of new reactor and furnace along with associated modifications  Requires high number of shutdown days for implementation  High Capex and Opex

Novel approach of CCRU Capacity Augmentation  Significant CCRU capacity augmentation without any major modification in CCRU  Low cost in nature  Significant energy saving Approach adopted (a) loading of more catalyst in existing reactors by changing reactor internals design (b) improving CCRU feed quality by revamping NSU for reformate yield improvement

Study and Analysis  Process study by licensor indicated significant additional catalyst loading possible by changing design of the reactor internals  Replacement of reactors concentric outer Johnson screen by scallop design envisage 22 % more catalyst loading in existing reactors  Correlative 22 % increase in T’put possible on account of catalyst activity due to additional catalyst loading

Concentric vs Scallop design internals Concentric design Internals Scallop design internals

Change in reactor catalyst inventory

Concentric outer grid vs Scallops internals of reactor 15R1 reactor 15R2 reactor 15R3 reactor Attribute Concentric Scallop Concentric Scallop Concentric Scallop Design Design Design Design Design Design Catalyst inventory, MT 4.9 5.54 9.8 11.73 17.3 22.37 Δ M Catalyst - +14% - +20% - +24% No. of scallop elements - 20 - 26 - 29 V gas in outer grid (m/s) 13.2 14.2 14.7 21.2 11.9 23.3 Δ (ΔP Catalyst Bed ) - +4% - +6% - +7%

Salient advantages of scallop design  Increases catalyst loading in existing reactors  Better catalyst activity on account of reduction of WHSV  Low cost and easy in installation  Good mechanical resistance  Only minor increase in catalytic bed pressure drop  Minimum catalyst loss in case of mechanical failure

Impact on ΔWAIT at Iso -RON 120 110 Concentric design RON Scallop design 100 Severity Gain : 5 deg c 90 80 5 10 15 20 ΔWAIT

Impact on ΔRON on Iso -WAIT 3 2.5 2 Concentric design ΔRON Scallop design 1.5 RON Gain : 0.9 1 0.5 0 516 518 520 522 WAIT

Performance improvement in CCRU by Scallop Installation  Catalyst inventory in reactor system increased by 22%  Combined catalyst inventory in all reactors increased from 33 to 40.8 MT  At Iso-RON, reduction of WHSV results in decrease of WAIT by 5 C  At Iso-WAIT, 0.9 RON increase on account additional catalyst  Post reactor internals modification, CCRU being operated at 20 % more than its earlier operating capacity

Reformate Yield improvement by Benzene precursor management  In-house simulation study indicated, Bz & its precursors can be reduced to < 1.0 vol % in CCRU feed by improving distillation in NSU  Low cost Naphtha splitter revamp was adopted for CCRU feed quality improvement along with capacity augmentation  NSU revamp entailed additional preheat exchangers, overhead condensers, product coolers and column internals modification

Reformate Yield improvement by Benzene precursor management  Post NSU revamp, benzene & its precursors in CCRU feed restricted to <1.0 % against original 4.0 vol %  Improved CCRU feed stock restricted Benzene in reformate stream to desired limit of <1.8 vol %  Reformate directly blended with Isomerate and De-sulphurised FCC gasoline to meet final MS specifications  As Bz in reformate is controlled, light reformate draw was stopped (12 % earlier) resulting in reformate yield increment by same extent  Stoppage of reformer splitter unit (RSU) offloaded ISOM unit capacity resulted in significant energy reduction

Low cost NSU revamp for reformate yield maximization Attributes Before Revamp After Revamp NSU Unit T’put, MT/hr 144 180 Preheat, deg c 95 145 ΔH,( Pre-heaters ), MKcal/hr - + 6.1 ΔH,( Overhead Condenser ), MKcal/hr - -5.22 ΔH,( Product Cooler ), MKcal/hr - -1.42 CCRU Feed, ( Bz, MCP and CH ) Vol % 4.0 <1.0

Benefits  CCRU reactors internals design change & low cost NSU revamp was executed in Aug-10  Scallops being in segments were found to be easy in installation and the job was completed in 17 engineering days  About 20 % CCRU capacity augmentation on account of additional catalyst loading  About 12 % reformate yield improvement on account of CCRU feed quality improvement.  Combined reformate yield improvement of 32 %  Energy saving of about 1200 SRFT/annum on account of stoppage of RSU & light reformate processing in ISOM unit

T Sudhakar Deputy Manager Indian Oil Corporation Limited, India T Sudhakar is working as Deputy Manager at Mathura Refinery, Indian oil Corporation Limited, India and is primarily responsible for rendering technical services for Continuous catalytic Reforming unit and Crude & Vacuum distillation units. He has 9 years of varied experience in process monitoring, simulations and operations. He holds Bachelor degree in Chemical Engg. from Shri Venkateswara college of Engg, Tamil Nadu, India. Email : sudhakart@iocl.co.in Phone : 0091-565-2417318